Electromechanical shutters are well known in the art and have been used in a number of applications, for example, in which light exposes a photosensitive surface. It is, of course, highly advantageous to miniaturize such shutters. Conventional electromechanical shutters are typically greater that 1 cubic centimeter in volume. The materials and methods for the fabrication of these devices are inadequate for the fabrication of micro-electromechanical shutters which are less than 1 cubic centimeter in volume.
Micro-Electromechanical Systems (MEMS) is a rapidly growing field that is impacting many applications today. Three-dimensional micro-engineered devices and systems involving silicon planar technology can be mass produced with features from one to a few hundred microns having tolerances in micron or sub-micron level. Most of the current micro-engineering technologies are evolved from the adaptation of thin films, photolithographic and etching technologies generally applied to silicon wafers on which silicon monoxide, silicon dioxide, silicon nitride, and the like, thin films are deposited and etched thereafter yielding planar configuration.
Although the planar silicon technology is capable of building a three-dimensional array, the process steps involved in building those structures are many and very often exceed 20 to 30 steps thus making the process less attractive for many applications. Furthermore, there are many complicated structures that are not possible to be incorporated in the silicon planar technology because of certain limitations of the thin film technology.
Moreover, experience indicates that the current planar silicon technologies using silicon substrates are inadequate for the fabrication of an integrated and self-contained three-dimensional arrays of micro-devices which can be used as solenoids, actuators, transformers, light shutters, and the like.
The limitation of the planar silicon technologies stems from the fact that the multi-step thin film technology coupled with etching processes which are usually used to build three-dimensional structures on a silicon wafer can not produce complex structures. As for example, one of the greatest drawbacks of the silicon technology is that it is not possible to build a buried helical coil or a uniform vertical cylindrical column having higher than 5:1 length to radius aspect ratio, and similar complex configurations. Furthermore, building three-dimensional multi-layered structures using thin film technology involves multiple process steps, generally twenty or more, and therefore makes this process not economically feasible.
Therefore, there persists a need for a method to fabricate integrated hybrid silicon-based micro devices which require fewer process steps thereby reducing production cycle time and increasing cost efficiency.